Kil'jaden is a five-phase encounter, with three main phases and two intermissions. He's got a lot of mechanics, and they interact with each other in different ways.
Phase One: From 100% to 80% health

Tanks, position the boss so that it is slightly outside the center circle (in which direction does not matter) and facing away from the raid.

Felclaws: anti-tank stacking DoT. Tanks swap at 5 stacks. (On Heroic, Felclaws will also do a cone of damage).

Rupturing Singularity: This drops a small sphere of dark energy in the center of the room, marked by a purple circle. Anyone caught INSIDE the point of impact when the sphere lands will be instantly killed. The players OUTSIDE the point of impact will be knocked back and take moderate damage.

--> When he casts Rupturing Sincularity, stand around the sphere but not inside the purple circle.

Armageddon: Meteors rain down on the platform. The impact points are marked by several SMALL and one LARGE red circle. The meteors take 7 seconds to reach the platform. The small meteors do moderate damage, while large meteors do massive damage, and both also apply a stacking 30-second DoT. If a meteor is NOT soaked, the raid will take heavy raid-wide damage and a raid-wide DoT.

--> We will divide the platform into quadrants and will assign a quarter of the raid to each quadrant. Each group should have some immunities and ability to remove the Fire debuffs. After Armageddon we have 7 seconds to get to the circles to soak them. The current inactive tank should soak the big red circle, while the current active tank should take one of the smaller circles (ideally a circle behind the tank). We only want ONE person per circle as the damage is not split between soakers.

Note 1: Armageddon occurs MORE FREQUENTLY than every 30 seconds, so if you soak two in a row you'll get two stacks of the debuff which is a LOT of damage. Rotate soakers or use immunities (like cloak of shadows) to clear the DoT.

Note 2: It is also possible for a player to soak the big red circle with a physical immunity, like Ice Block.

Erupting Reflection: Kil'jaeden makes copies of several targeted players. These will begin to cast Erupting Dreadflame, which does moderate raid-wide damage (on heroic, they will also apply a stacking self-buff to nearby reflections with each cast).

--> Eliminate these asap. We can stack them and cleave them down (on Heroic we'll need the affected players to stand apart as they reflections buff each other).
PHASE TWO: Intermission. Occurs at 80% health.

At 80% health Kil'jaden will fly up and shield himself with Nether Gale. This phase lasts 60 seconds.

He'll continue to cast Armageddon (the red circles we need to soak) and Rupturing Singularity (dark sphere with knockback), but the spheres will spawn at the corners of the room instead of the center.

He'll also cast Bursting Dreadflame debuff, which looks like a giant red circle centered on several players. Move this to the EDGE of the platform if you have it, and run out of the red circles if you don't. This may co-occur with Armageddon. Icy veins suggests running the Dreadflames to the front, back, or sides of the platform (N, S, E, W) as the singularities will be in the corners (NW, NE, SW, SE), and the Armageddon circles are most likely to occur in the middle of each quadrant.

Focused Dreadflame: targets a player and inflicts massive fire damage in a line between the boss and the target. The damage is dicvided between all players hit.

--> We need to stand in a line on the person with Focused Dreadflame. Players with immunities can also negate this attack.

The boss will exit the fight and will shroud the entire raid in the shadow of Deceiver's Veil. This ability restricts the raid's vision and ability to target any allies or enemies to 8 yards. It also causes healing to be reduced by 100% and causes all spells and attacks to miss beyond 8 yards.

The entire raid will also be affected by Choking Shadow, which absorbs more and more healing (by players within 8 yards) the longer you remain in Deceiver's Veil.

Lord Illidan will fly to the platform periodically during Deceiver's Veil. Any players who move within 8 yards of him are granted Illidan's Sightless Gaze which allows us to see and hit all enemies and heal allies within a 40 yard radius.

Adds called Shadowsouls will spawn throughout the platform at the start of this phase. We will continually take damage from their casts (Destabilized Shadowsoul.)

Rupturing Singularity continues, and it's back to the corners of the room.

--> The raid will group up in the center of the platform so everyone can receive healing. Healers should conserve mana, as healing is continually reduced. Alacrity is very important in this phase. When Illidan flies to the platform, we must find him in the fog to receive his buff, which grants us vision in a 40 yard radius, the ability to heal allies and damage foes, but at a cost. The raid will take fire damage for 20 seconds.

Once we get the buff, we need to eliminate the Shadowsoul adds as quickly as possible. Once they are dead we enter the last phase.

Phase Five: 40% to the end.

He continues to use Felclaws (the anti-tank attack), Bursting Dreadflame (big red circles we need to take to the edge) and Focused Dreadflame (the line attack that shares damage).

The key new mechanic of this phase is Tear Rift. This spawns a demonic rift which draws in all nearby players, missiles, and flame pools. Nearby players are also afflicted with Gravity Squeeze, a debuff that does heavy damage that increases every tick.

Kil'jaeden also starts using his ultimate attack, Darkness of a Thousand Souls, which inflicts massive shadow damage right away and heavy shadow damage every 2 seconds for the remainder of the encounter. If players are standing in a Tear Rift, however, the missiles targeting them will instead be harmlessly sucked into the rift.

--> When Darkness of a Thousand Souls is cast, all players must gather INSIDE the rift to avoid the damage. Anyone NOT inside the rift will die as they'll take heavy ticking damage for the rest of the encounter.

However, anyone inside the rift will also take heavy damage from Gravity Squeeze, which increases over time. So we'll need to time our Rift entry very carefully, entering the rift at the last moment and getting out right after the Darkness of a Thousand Souls cast concludes. We will likely need to use raid cooldowns.

He will also create Demonic Obelisks which spawn around the platform and detonate in a cross of fel energy connecting them. Anyone hit takes a lot of damage and is knocked back.

Flaming Orbs target players and spawn a flame sphere. These spheres chase the targeted players until they impact, which deals a Flaming Detonation AoE and leaves a fiery void zone. The size of the pool is reduced based on the length of time the sphere chased the player. Anyone inside the pool takes damage. The pools will be sucked into any nearby Tear Rifts that spawn.

--> Targeted players should take their orbs to the corners of the room before letting them impact, as the orbs explode and drop a void zone upon impact.

This is a five-phase fight, with three main phases and two intermissions.

PHASE ONE: from 100 to 80%

* Position boss slightly outside the center circle.
* Tanks, swap at 5 stacks of Felclaws.
* Purple orb in center of room ("Rupturing Singularity"). Does a knockback. Group AROUND the sphere but not inside its purple circle. (Standing inside purple circle is lethal).
* Red swirls ("Armageddon"): there will be 1 big red swirl and several little ones. These need to be soaked. We'll divide platform & raid into quadrants for these. Current off-tank or player with physical immunities should soak the big red one. The Dot is NASTY: Rotate soakers so you don't get multiple stacks of the DoT, or have players with immunities soak them (e.g. rogues can cloak it off)
* Kill the reflection adds ("Erupting Reflection").

PHASE TWO: Aerial intermission. Occurs at 80% and lasts 60 seconds.

* The purple orbs (rupturing singularities) will now appear in the CORNERS of the platform (NW, NE, SW, SE) instead of the center.

* If you get the BIG red circle centered on you ("Bursting Dreadflame"), take it to the edge. Everyone else, get out of the big red circles. Try to take it to the cardinal directions of the platform (platform's N, S, E, W) to reduce conflicts with the purple orbs which appear in the corners, and Armageddon red swirls which occur in the four quadrants.

* When someone gets the BIG RED ARROW (Focused Dreadflame) stand on the line between that player and the boss.

PHASE THREE: From 80 to 40% health. Combination of the previous two phases.

The purple orb spawns at the center of the room again. Take the big red circles to the edge, group around the purple orb but not under it, stand in the line with the red-arrow person, kill the reflection adds, tanks swap with 5 stacks of Felclaws.

The raid will be shrouded in darkness. Group up at the center of the platform for healing. Healers should conserve mana as healing will be continually reduced during this phase. Find Illidan in the darkness on the platform to get his buff which lets us see through the darkness. Once we get the buff, kill all the adds (Shadowsouls).

We'll still get purple orbs during this phase, they'll spawn at the corners of the room again.

PHASE FIVE: Final phase. 40% to the end.

Run the big red circles to the edge and stand in the line, tanks swap the Felclaws debuff as before.

But there's a new mechanic in this phase: Tear Rift, which spawns in a corner of the room and sucks in all nearby players, missiles and void zones. It also debuffs players with an increasing DoT ("Gravity Squeeze") while you're in it. We'll need to STAND IN the rifts to avoid his biggest attack, Darkness of a Thousand Souls, which does massive damage right away and heavy shadow damage every 2 seconds for the rest of the encounter to anyone struck by it. Anyone NOT in the rift when he casts this will probably die.

However, when we're standing in the rift we'll also be taking increasing damage, so we need to time our entry very carefully: enter the rift at the last moment before the Darkness of a Thousand Souls cast, then get out right after the cast concludes.

He'll also create Demonic Obelisks around the platform which detonate in a cross of fel energy connecting them and do a knockback. Get out of the lines that connect these obelisks.

Lastly, kite the Flaming Orbs to the edge to drop the fiery void zones. The longer you kite the orbs, the smaller the void zone will be. You can't avoid the orbs.

So, for Phase Five:

* Stack in the Rift for Darkness of a Thousand Souls, then get out again.
* Avoid the lines between the obelisks
* Take the flaming orbs and the big red circles to the edge
* Stand in the line with the red arrow player

Okay, here's what's new with heroic Kil'Jaeden! He does more damage, but there are also a number of mechanical changes to the fight too.

Phase One

* The Shadow Reflection: Erupting adds that spawn on random players' positions, and are copies of those players, now spawn in Phase One as well as Phase Two. AND these adds will now buff each other if they're within 20 yards of each other with a stacking damage buff (called Eruption, which gets a new stack every time the adds cast Erupting Dreadflame).

--> Strategy: Option #1: The marked players spread out to make sure the adds spawn at least 20 yards apart. Option #2: Marked players run to melee to stack the adds up anyway so we can cleave them down QUICKLY. If we stack the adds like this they MUST be killed before the third cast or their damage will be so high they'll start one-shotting people.

Intermission One

* The Rupturing Singularities -- the purple orbs that slowly fall to the platform and (a) kill anyone directly beneath them, but also (b) knock back everyone else -- now spawn in this phase. They will spawn in the corners of the room.

--> Strategy: When an orb spawns you must get to the orb's quadrant of the platform so you don't get knocked off. Don't stand beneath the orb to the orb's landing zone though or it will kill you. Keep an eye on the timers so you don't get caught out!

* Kil'Jaeden's Focused Dreadflame -- the line attack that we must stand in to split damage -- now causes players in the line to do splash damage to others within 5 yards.

--> Strategy: when standing in the line, spread out to keep raid damage to a minimum!

Phase Two

* The tanks will get debuffed with Shadow Reflection: Wailing. This is a new add that is a copy of the tank. It's on a different timer from the raid's Shadow Reflection: Erupting adds. The mechanic starts with a 7 second debuff, which spawns an add when it expires. This add will need to be tanked and will occasionally cast Sorrowful Wail, which deals damage to all players within 10 yards. Each cast buffs the add with a stack of Crescendo, a nasty self-buff which greatly increases the add's damage AND the radius of its effect by 5 yards.

--> Strategy: The raid needs to kill this add before its Crescendo stacks get too high. Tanks keep the add underneath the boss so we can cleave it, but drag it away when it casts Sorrowful Wail.

Intermission Two: Darkness phase

No changes from normal mode, YAY! As on normal, the platform is shrouded in darkness and we need to find Illidan to get the buff which lets us see, then kill all the adds (Shadowsouls) to end this phase.

Phase Three

In addition to all the other mechanics of Phase Three, Kil'Jaeden will spawn a Flaming Orb. This orb spawns in a targeted location, which looks like an orange swirl. The orb then follows the player closest to it when it spawns. It will follow the player indefinitely. Once it reaches the player it will trigger a Flaming Detonation, which does high damage to all players within 10 yards and creates a burning void zone. The size of the pool of fire is INVERSELY proportional to the length of time it took for the orb to detonate. ALSO, if the pool falls near a Tear Rift portal, the Rift will remove the void zone.

--> Strategy: We want to kite the orb into a rift. When the orb's location is marked, a mobile ranged DPS should be the closest one to it. All other players should move away. That player should then kite the orb toward the rift. Let the orb touch you right next to the portal.

Okay, here's the write-up which includes the heroic changes. We haven't done him for a while on normal so some of the normal mechanics may be a little rusty, too. Here goes!

This is a five-phase fight, with three main phases and two intermissions.

PHASE ONE: from 100 to 80%

* Position boss slightly outside the center circle.
* Tanks, swap at 5 stacks of Felclaws.
* Purple orb in center of room ("Rupturing Singularity"). Does a knockback. Group AROUND the sphere but not inside its purple circle. (Standing inside purple circle is lethal).
* Red swirls ("Armageddon"): there will be 1 big red swirl and several little ones. These need to be soaked. We'll divide platform & raid into quadrants for these. Current off-tank or player with physical immunities should soak the big red one. The Dot is NASTY: Rotate soakers so you don't get multiple stacks of the DoT, or have players with immunities soak them (e.g. rogues can cloak it off)
* (Heroic): We'll be getting Shadow Reflection adds which spawn at a few players' locations. On heroic they'll buff each other if they're standing within 20 yards of each other. The marked players either need to collapse to ensure the adds spawn in melee and can be cleaved fast (before the third cast), or the marked players need to spread out by 20 yards and we'll kill the adds one by one.

Movement in Phase One:
* Raid stands slightly outside the center circle -- this means you won't have to move much for the orb. TANKS, make sure to scoot in toward the orb so you don't get punted off the platform.
* Spread out to soak the red swirls. Tanks or people with immunities soak the big ones.
* Marked players either collapse for adds or spread 20 yards apart.

* If you get the BIG red circle centered on you ("Bursting Dreadflame"), take it to the edge. Everyone else, get out of the big red circles. Try to take it to the cardinal directions of the platform (platform's N, S, E, W) to reduce conflicts with the purple orbs which appear in the corners, and Armageddon red swirls which occur in the four quadrants.

* When someone gets the BIG RED ARROW (Focused Dreadflame) stand on the line between that player and the boss. (Heroic): We now need to stand at least 5 yards apart to avoid inflicting splash damage on each other.

* (Heroic): The Rupturing Singularities (the purple orbs that do a knock-back) will spawn in the corners of the platform during this phase. Get to the orb's quadrant to avoid being knocked back. Don't stand beneath the orb or it will kill you.

Movement in intermission:
* If you get a big red circle, take it to a straight edge of the platform (not a corner). Everyone else, get out of the big red circles.
* Purple orbs will spawn in the corners. Get to the orb's quadrant to keep from getting punted off.
* NOTE for players with BIG RED CIRCLE during orb: Pay attention to orb timing! Don't get punted off the platform by the orb! Run your circle closer to the orb, not to the far side.
* When someone gets the big red arrow, stand in the line, staying more than 5 yards apart from each other.

PHASE TWO: From 80 to 40% health. Combination of the previous two phases.

The purple orb spawns at the center of the room again. Take the big red circles to the edge, group around the purple orb but not under it, stand in the line with the red-arrow person, kill the reflection adds, tanks swap with 5 stacks of Felclaws.

* (Heroic): the tanks will now get a Shadow Reflection: Wailing add. Tank this add under the boss so we can cleave it down, BUT pull it out when it casts Sorrowful Wail which does damage within 10 yards. We need to kill it fast because every wail will give the add a nasty self-buff (Crescendo).

Movement in Phase Two:
* Group around the purple orb but not under it
* Take the big red circles to the edge (don't get punted off by the orb)!
* Stand in line with red-arrow person
* Kill the reflection adds AND the tank's add; tanks drag your add out when it casts Sorrowful Wail.

The raid will be shrouded in darkness. Group up at the center of the platform for healing. Healers should conserve mana as healing will be continually reduced during this phase. Find Illidan in the darkness on the platform to get his buff which lets us see through the darkness. Once we get the buff, kill all the adds (Shadowsouls).

We'll still get purple orbs during this phase, they'll spawn at the corners of the room again.

Movement in Intermission Two:
* Run around to find Illidan & get his buff
* Now that you can see run around killing adds
* There will be purple orbs in corners: get to the orb's quadrant!

PHASE THREE: Final phase. 40% to the end.

Run the big red circles to the edge and stand in the line, tanks swap the Felclaws debuff as before.

But there's a new mechanic in this phase: Tear Rift, which spawns in a corner of the room and sucks in all nearby players, missiles and void zones. It also debuffs players with an increasing DoT ("Gravity Squeeze") while you're in it. We'll need to STAND IN the rifts to avoid his biggest attack, Darkness of a Thousand Souls, which does massive damage right away and heavy shadow damage every 2 seconds for the rest of the encounter to anyone struck by it. Anyone NOT in the rift when he casts this will probably die.

However, when we're standing in the rift we'll also be taking increasing damage, so we need to time our entry very carefully: enter the rift at the last moment before the Darkness of a Thousand Souls cast, then get out right after the cast concludes.

He'll also create Demonic Obelisks around the platform which detonate in a cross of fel energy connecting them and do a knockback. Get out of the lines that connect these obelisks.

* (Heroic): A ranged DPS shold pick up Flaming Orb and drag it to a rift, which will get rid of the void zone. Failing that, kite it to the edge. The longer you kite the orb, the smaller its void zone will be.

So, for Phase Five:

* Stack in the Rift for the end of the Darkness of a Thousand Souls cast , then get out again.
* Avoid the lines between the obelisks
* One Ranged DPS take the flaming orbs to the rift. Failing that, to the edge.
* Take the big red circles to the edge.
* Stand in the line with the red arrow player, but not too close together

We made great progress last night! We got him reliably through Phase One, several times through Intermission One, and into Phase Two, and on our last attempt we got him well into Phase Two!

Here's some of the stuff we figured out:

1. Pulling the reflection adds apart worked best. We pulled them to three points on the circle, about 20 yards apart, and killed them one by one. That worked fine.

2. Only about four people need to stand in the line ("Focused Dreadflame"). That's enough to share the damage, and having fewer people in the line means less chance of splash damage, and it means that the rest of the raid can continue handling the other mechanics, DPSing etc.

3. During the first intermission, and at a few other points during the encounter, the Big Red Circles ("Bursting Dreadflame") detonate a few seconds BEFORE the orange swirls ("Armageddon"). This explosion LOOKS like Armageddon going off. Some of the soakers (including me!) are led to think Armageddon has gone off and step off the swirls, which leaves them unsoaked. Armageddon then goes off for real, the whole raid gets the nasty DoT from the unsoaked swirl, and we wipe shortly thereafter.

--> It is CRITICAL for everyone to stay on their orange swirl until it disappears. Watch your feet! Wait for the swirl to disappear! Don't be fooled by the orange explosion a few seconds ahead of time!